He's a tough professor, no doubt about it. But his classes are extremely engaging because he will call on anyone on the spot. Sometimes he can go a bit fast, but you will learn. Just go to class, stay awake and you'll learn. His tests are usually like 3 or so questions. They are typically fair, basic you just have to KNOW the equation. Definitely a MUST prof at UCLA.
This is my first review after completing 3 years here and deservingly so because like others said, I also believe he is the best professor in the MAE department. I took 105A with Prof. Amar, which got me interested in this course. And if you have taken a course with him, you know how effective he is at teaching since he teaches through examples with actual numbers, but had to deal with his tricky quizzes and exams. Prof. Marner is even more effective than Amar, without the tricky exams. Marner uploaded lecture outlines before each lecture so that class would flow more smoothly and save our hand muscles because he cares about his students. Just go to class and complete his lecture notes and that will be all you need in order to succeed in his class. He does simple and short derivations (the First Law of Thermodynamics will be used a lot), but then dives right into sample problems to help you understand the material because nobody likes being bored by derivations using countless variables. He also gets the class involved by calling on students to help him solve the problems to make the lectures less boring because if someone gets something wrong he will make fun of him/her in a non-condescending manner. Don't worry if he makes fun of you though, he is like a loving father like others said. You can read the textbook (Moran and Shapiro) for some clarification, but his notes are good enough to complete 90% of the homework problems. Problem sets consisted of 5 problems, usually 2 from the text and the 3 others from outside sources. You will do well on his exams if you understand the homework because the exams are at the same difficulty level as the homework problems, which aren't too difficult to begin with. And don't slack off on the design project. My group did and frantically put a 20 page report together all during 9th and 10th week, but luckily the TA, Mike, was a generous grader even though he seemed stringent about grading when I talked to him about the past reports. All in all, you will learn a lot in this class, not just thermodynamics but also life lessons. After the final exam, he shook everyone's hands, stated their names, and thanked them for being a part of his class. I wished he had thought me heat transfer as well.
Winter 2021 - This course is very straightforward and covers all the basics of many different thermodynamic cycles, engines, etc. I have no interest in this subject so I found that a bit draining. However, the professor's explanations are very straightforward and it is not too difficult to pick up the new concepts. The homework assignments were challenging and often frustrating as they relied on methods that were not well explained in the class. Also be prepared to spend hours looking up values in the tables. The midterm exam was awful, not that difficult but it was waaaay too long, it took me about 7 hours to complete in total. I don't know why professors during COVID are deciding its ok to give students a 24-hour exam window and then assign an exam that takes 7-10 hours to complete fully (this is not the first class that has done it). If a normal exam window is 2 hours, the exam should be designed with that time window in mind! Also, the group project was rough as we were given very little instruction or guidance (no examples to work from), we had to do it basically from scratch.